Terrestrial and aquatic herbicidal methods

ABSTRACT

This invention concerns the use of certain 3-[5- or 3-substituted-1,2,4-oxadiazol-3- or -5-yl]-1-substituted-4-substituted-5-substituted or unsubstituted-2-imidazolidinones to control growth of terrestrial or aquatic plants.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of application Serial No. 626,916, filed July 2,1986, which is a continuation-in-part of application Ser. No. 544,938filed Oct. 24, 1983 since abandoned which is a division of applicationSer. No. 348,479 filed Feb. 12, 1982, now U.S. Pat. No. 4,426,527.

FIELD OF THE INVENTION

This invention concerns certain 3-[5- or3-substituted-1,2,4-oxadiazol-3-or-5-y1]-1-substituted-4-substituted-5-substituted orunsubstituted-2-imidazolidinones having herbicidal activity and the usethereof to control terrestrial or aquatic vegetation.

DESCRIPTION OF THE INVENTION

This invention concerns methods for controlling undesirable terrestrialor aquatic vegetation. More particularly the invention is directed tomethods for controlling the growth of undesirable terrestrial or aquaticplants by contacting the terrestrial or aquatic plants with aherbicidally effective amount of 3-[5- or3-substituted,1,2,4-oxadiazol-3-or-5-y1]-1-substituted-4-substituted-5-substituted orunsubstituted2-imidazolidinones represented by the formula: ##STR1##wherein:

A is ##STR2##

R is alkyl or haloalkyl of up to 6 carbon atoms, cycloalkyl of from 3 to8 carbon atoms, alkenyl or alkynyl of up to 5 carbon atoms, --R⁴ --O--R⁵R⁴ -S-R⁵ wherein R⁴ is alkylene of up to 6 carbon atoms and R⁵ is alkylof up to 6 carbon atoms, ##STR3## wherein Z is nitro, halogen,trifluoromethyl or R⁵ and n is 0, 1, 2, or 3; R¹ is hydroxy, halogen,##STR4## wherein R⁶ is alkyl or haloalkyl of up to 6 carbon atoms,cycloalkyl of from 3 to 8 carbon atoms, alkenyl or alkynyl of up to 5carbon atoms or ##STR5## wherein Z¹ is nitro, halogen, trifluoromethyl,alkyl or alkoxy of up to 8 carbon atoms and n is 0, 1, 2 or 3 or##STR6## wherein R⁷ and R⁸ are the same or different and representhydrogen, alkyl or haloalkyl of up to 6 carbon atoms; or R₇ can be##STR7##

R² is hydrogen, hydroxy, alkyl, or haloalkyl of up to 4 carbon atoms orallyl; and

R³ is alkyl of up to 3 carbon atoms or allyl.

Some alkyl groups of which the various constituents in the above formulaare representative are, for example, methyl, ethyl, n-propyl, isopropyl,n-butyl, iso-butyl, sec-butyl, pentyl, hexyl, or the like, includingcombinations thereof, e.g., 1,1-dimethylethyl. Exemplary alkoxy groupsare methoxy, ethoxy, propoxy, butoxy, octoxy, and the like. As examplesof cycloalkyl groups there may be mentioned cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cyclopentyl, and cyclooctyl. Allyl, butenyl,pentyl, propynyl, butynyl, pentynyl and the like are exemplary ofsuitable alkenyl and alkynyl groups represented by the variousconstituents in the above formula. Representative suitable alkylenegroups are, for example, methylene, ethylene, propylene, butylene,pentylene, or hexylene. As the halogen substituents, there may bementioned chlorine, bromine, iodine, or fluorine, preferably chlorine orbromine.

Preferred compounds useful according to this invention are those whereinR and R³ are alkyl, R¹ is hydroxy, R² is hydrogen or hydroxy and X isoxygen, some examples of which are3-[5-(1,1-dimethylethyl)-1,2,4-oxadiazol-3-y1]-1-methyl-4-hydroxy-2-imidazolidinone,3-5-(1,1-diemthylethyl)-1,2,4-oxadiazol-3-y1]-1-methyl-4,5-dihydroxy-2-imidazolidineoneand3-[3-(1,1-dimethylethyl)-1,2,4-oxadiazol-5-y1]-1-methyl-4,5-dihydroxy-2-imidazolidinone.As exemplary of additional compounds believed to have herbicidalactivity in accordance with this invention, there may be mentioned3-[5-(1,1-dimethylethyl-1,2,4-oxadiazol-3-y1]-1-methyl-4-acetoxy-2-imidazolidinone,3-[5-(1.1-dimethylethyl)-1,2,4-oxadiazol-3-y1and3-[5-(1,1-dimethylethyl)-1,2,4-oxadiazol-3-y1]-1-methyl-4-butyryloxy-2-imidazolidinone.

Useful compounds of this invention of the 3-y1 series wherein R¹ ishydroxy and R² is other than hydroxy, e.g., hydrogen, may convenientlybe prepared by reacting, in a first step, an appropriately substitutedcarbonyl chloride of the formula R-C0C1, where R is as previouslydefined with cyanamide to prepare a compound of the formula R-CO-NHCN.This reaction is typically conducted in a cold, alkaline reaction mediumthe reaction product being crystallized by treatment of the reactionmixture with a cold, dilute aqueous acidic salt solution, e.g., diluteaqueous hydrochloric acid saturated with sodium chloride.

In a second step, the isolated reaction product from step one is reactedwith hydroxylamine hydrochloride in the presence of an acid acceptor toprepare the corresponding 3-amino-5-(substituted)-1,2,4-oxadiazole ofthe formula: ##STR8##

Useful compounds of the 5-y1 series may be prepared by reaction of anappropriate nitrile of the formula R-CN where R is as previouslydefined, with an alcohol and hydrogen chloride, followed by reactionwith cyanamide and then with hydroxylamine as described by K. R. Huffmanand F. C. Schaefer, J. Org. Chem. 28, 1816 (1963) to give thecorresponding 5-amino-3-(substituted)-1,2,4-oxadiazole of the formula:##STR9## The isoxazolamine is then phosgenated to the correspongisocyanate of the formula A--NCO wherein A is as previously defined. Theisoxyanate is then reacted in a third step, with an appropriatelysubstituted amino acetaldehyde dialkyl acetal of the formula R³--NH--CH(R²)CH(OR⁹)₂, wherein R² and R³ are as previously defined and R⁹is alkyl of up to 6 carbon atomns or -CH(OR⁹) forms a 5 to 6 memberedheterocyclic ring which may contain up to 3 hereto atoms to form anacetal urea of the formula: ##STR10##

In the final step the acetal urea is hydrolyzed by heating in a diluteaqueous acid medium, e.g., hydrochloric acid, to form a compound of theinvention wherein R¹ is hydroxy.

If it is desired to prepare a compound useful according to the inventionwherein both R¹ and R² are hydroxy, a 3- or 5-amino-3- or5-(substituted)-1,2,4 oxadiazol (prepared as described previously) isreacted with an appropriately substituted isocyanate of the formula R³--N═C═O, wherein R³ is a as previously defined to form a urea of theformula A--N(H)--C(O)----N(R³)--H which is reacted with glyoxal to forma compound useful according to the invention having a hydroxysubstituent in both the R¹ and R² positions.

A useful compound of the invention wherein R¹ is halogen, e.g., chlorineor bromine, may be prepared by reacting a compount of the invention ofthe formula: ##STR11## wherein A, R² and R³ are as previously definedwith a suitable halogenating agent typically in the presence of an inertsolvent and optionally in the presence of an acid binding agent. When itis is desired to halogenate useful compounds of the invention whereinboth R¹ and R² are hydroxy, it is necessary to protect the hydroxy groupat the R² position by, for example, alkylation followed by removal ofthe alkyl group subsequent to halogenation.

To prepare a useful compound of the invention wherein R¹ is ##STR12## acompound of the invention having the formula: is reacted with ananhydride of the formula: ##STR13## is reacted with an anhydride of theformula: ##STR14## wherein A, R², R³ and R⁶ areas previously defined.This reaction is typically conducted at reflux temperature in thepresence of an acid acceptor such as triethylamine, pyridine,N,N-dimethylaniline or the like and in the presence of an inert solventsuch as benzene, methylene chloride, chloroform, ethyl acetate,tetrahydrofuran or the like.

It is, of course, to be realized that all of the abovedescribed modes ofpreparation employ well-known analytic techniques and that any usefulcompound within the scope of the invention may readily be prepared byone skilled in the art using the same or similar methods. Synthesis of aspecific compound useful according to this invention is illustrated bythe following Example:

EXAMPLE I Preparation of3-[5-(1,1-dimethylethyl)-1,2,4-oxadiazol-3-yl]-1-methyl-4-hydroxy-2-imidazolidinone

(a) To a flask provided with a magnetic stirrer was charged 160milliliters of 10 percent aqueous sodium hydroxide and 34 grams of a 50percent aqueous cyanamide solution. The flask contents were maintainedat a temperature in the range of 0° to 5° C. by immersion in a salt andice bath. To the cold solution was added dropwise, with contactstirring, 50 milliliters (0.4 mole) of trimethylacetyl chloride. Afteraddition of about 0.2 mole of trimethylacetyl chloride, sufficientadditional aqueous sodium hydroxide solution was added to maintain a pHof about 10. The reaction mixture was stirred in the ice bath forone-half hour, after which the ice bath was removed and stirring wascontinued for an additional one-half hour. Cold dilute aqueoushydrochloric acid saturated with sodium chloride was then added untilthe mixture turned milky and crystal formation was observed. Thecrystalline material was separated by filtration, suction dried anddried in a vacuum oven yielding about 40 grams of dried material.

(b) The crystalline material prepared in paragraph (a) of this Examplewas added incrementally, with stirring, to a mixture of 25 grams ofhydroxylamine hydrochloride in 125 milliliters of pyridine, thetemperature of the reaction mixture being maintained below 40° C. A mildexotherm was observed. After addition was complete, the reaction mixturewas stirred over the weekend at ambient temperature. The reactionmixture was then diluted with 100 milliliters of water and 100milliliters of 30 percent aqueous sodium hydroxide, the latter added infour increments. After phase separation, the organic layer was removedand concentrated on a rotary evaporator to remove pyridine leaving anoily residue which crystallized upon addition of saturated aqueoussodium chloride. A total of 24.77 grams of crystals melting at 81° to83° C. were obtained.

(c) To a 500 milliliter flask provided with a paddle stirrer, a gasinlet tube, and a dry ice condenser fitted with a drying tube wascharged 20 grams of the crystalline material prepared in paragraph (b)of this Example dissolved in 400 milliliters of toluene. Dry hydrogenchloride gas was added resulting in the formation of a voluminousprecipitate after which phosgene was bubbled in below the liquid surfaceresulting in dissolution of most of the precipitate. The reactionmixture was stirred overnight at ambient temperature and then gentlywarmed to remove excess phosgene. Considerable frothing was observeduntil the temperature reached about 70° C. The flask was then purgedwith nitrogen at a temperature of 70 to 80° C. for about 8 hours afterwhich heating was discontinued and nitrogen purging continued overnight.The mixture was stripped on a rotary evaporator to remove tolueneleaving a white-yellow solid. The solid was placed in a vacuum oven atmoderate heat. When sublimation of the solid was noted, the solid wasremoved from the oven, 20 grams of solid material being obtained.

(d) To a flask provided with reflux condenser and magnetic stirring barwas charged 3.14 grams of the solid material prepared as described inparagraph (c) of this Example dissolved in 75 milliliters of toluene and2.4 grams of methylamino acetaldehyde dimethylacetal. The mixture wasstirred for one hour at ambient temperature and then slowly heated tojust below reflux temperature and maintained at this temperature, withstirring overnight. The mixture was then cooled, filtered and strippedon a rotary evaporator to remove toluene leaving an oily residue. Theoil residue was then stirred vigorously with 75 milliliters of watercontaining 0.75 milliliter of concentrated sulfuric acid. The mixturewas then gradually heated, with stirring, to 80° C. and maintained atthis temperature for one-half hour, most of the oil going into solution.The reaction mixture was then filtered to remove undissolved oil and theclear aqueous solution was extracted with two 75-milliliter portions ofchloroform. The combined chloroform extracts were concentrated on arotary evaporator leaving an oily residue which crystallized uponcooling and addition of a small amount of diethyl ether. Afterfiltration and washing with diethyl ether, 1.5 grams of crystallineproduct were obtained melting at 125° to 129° C., and identified by massspectrum and NMR analyses as3-[5-(1,1-dimethylethyl)-1,2,4-oxadiazol3-y1]-1-methyl-4-hydroxy-2-imidazolidinone.

The mode of synthesis of a specific compound useful according to thisinvention has been illustrated by the foregoing Example; but it is to beunderstood that any compound contemplated within the scope of thisinvention may be prepared by those skilled in the art simply by varyingthe choice of starting materials and using the illustrated techniques orother suitable techniques.

The compounds of this invention are believed effective in regulating thegrowth of a variety of undesirable terrestrial plants, i.e., weeds, whenapplied, in an herbicidally effective amount, to the growth medium,i.e., the soil, prior to emergence of the weeds or to the weedssubsequent to emergence from the growth medium.

The term "herbicidally effective amount⃡ is that amount of a compound ofthis invention required to so injure or damage weeds such that the weedsare incapable of recovering following application. It is, of course,understood that the compound, in addition to providing satisfactory weedcontrol, must not cause significant damage to any crop amongst which theweeds are growing. The quantity of a compound of this invention appliedin order to exhibit a satisfactory herbicidal effect may vary over awide range and depends on a variety of factors, such as, for example,hardiness of a particular weeds species, extent of weed infestation,climatic conditions, soil conditions, method of application, and thelike. Typically, as little as 0.2 or less pound per acre of a compoundof this invention would be expected to provide satisfactory weedcontrol, although in some instances application rates in excess of onepound per acre; e.g., up to 5 or more pounds per acre might be required.Of course, the efficacy of a particular compound against a particularweed species may readily be determined by routine laboratory or fieldtesting in a manner well known to the art. It is expected thatsatisfactory weed control can be had at a rate of application in therange of 0.01 to 1.0 pound per acre.

Of course, a compound of this invention can be formulated according toroutine methods with any of several known and commonly used herbicidaldiluents, adjuvants and carriers. The formulations can contain liquidcarriers and adjuvants such as organic solvents, as well as emulsifiers,stabilizers, dispersants, suspending agents, spreaders, penetrants,wetting agents and the like. Typical carriers utilized in dryformulations include clay, talc, diatomaceous earth, silica and thelike. Preferred formulations are those in the form of wettable powders,flowables, dispersible granulates or aqueous emulsifiable concentrateswhich can be diluted with water at the site of application. Also, dryformulations such as granules, dust, and the like, may be used.

When desired, a compound of this invention can be applied in combinationwith other herbicidal agents in an effort to achieve even broadervegetative control. Typical herbicides which can be convenientlycombined with Formula I compound include atrazine, herxazinone,metribuzin, ametryn, cyanazine, cyprazine, prometon, prometryn,propazine, simazine, terbutryn, propham, alachlor, acifluorfen,bentazon, metolachlor and N,N-dialkyl thiocarbamates such as EPTC,butylate or vernolate. These, as well as other herbicides described, forexample, in the Herbicide Handbook of the Weed Science Society ofAmerica, may be used in combination with a compound or compounds of theinvention. Typically such formulations will contain from about 5 toabout 95 percent by weight of a compound of this invention.

The herbicidal formulations contemplated herein can be applied by any ofseveral method known to the art. Generally, for formulation will besurface applied as an aqueous spray. Such applications can be carriedout by conventional ground equipment, of if desired, the sprays can beaerially applied. Soil incorporation of such surface applied herbicidesis accomplished by natural leaching, and is, of course, facilitated bynatural rainfall and melting snow. If desired, however, the herbicidescan be incorporated into the soil by conventional tillage means.

The compound prepared as described in Examples I was screened forherbicidal efficacy, against a variety of broadleaf and grassy weedspecies, under controlled laboratory conditions of light, humidity andtemperature. A solvent solution of said compound was applied, bothpreemergence and postemergence, to test flats containing the variousweed species, and herbicidal efficacy was determined by visualinspection, periodically after application of the compounds. Herbicidalefficacy was determined on a Numerical Injury Rating scale of from 0 (noinjury) to 10 (all plants dead).

The following Table sets forth Numerical Injury Ratings of the compoundprepared in Example 1 against a variety of common weed species atapplication rates of 10 pounds per acre preemergence and 10 pounds peracre postemergence. The Numerical Injury Ratings were determined twentyone days subsequent to application.

    ______________________________________                                        Weed:    Pre              Post                                                ______________________________________                                        Teaweed            10     10                                                  Jimsonweed         10     10                                                  Wild Mustard       10     10                                                  Coffeeweed         9      10                                                  Velvetleaf         10     10                                                  Tall Morningglory  9      9                                                   Yellow Nutsedge    4      10                                                  Yellow Foxtail     10     10                                                  Large Crabgrass    9      --                                                  Johnsongrass       10     6                                                   Wild Oats          10     10                                                  Barnyardgrass      10     9                                                   ______________________________________                                    

Based on said screening test, the compounds of this invention could beused for preemergence or postemergence control of a wide variety ofbroadleaf and grassy weeds. Typical of the various species ofterrestrial vegetative growth that may be controlled, combated, oreliminated are, for example, annuals such as pigweeds, lambsquarters,foxtail, crabgrass, wild mustard, field pennycress, ryegrass, goosegrass, chickweed, wild oats, velevetleaf, pursiane, barnyardgrass,smartweed, knotweed, cocklebur, kochia, medic, ragweed, hempnettle,spurrey, pondweed, carpetweed, morningglory, ducksalad, cheatgrass, fallpanicum, jimsonweed, witchgrass, watergrass, wild turnip, and similarannual grasses and weeds. Biennials that may be controlled include wildbarley, campion, burdock, bull thistle, roundleaved mallow, purple starthistle, and the like. Also controlled by the compounds of thisinvention are perennials such as quackgrass, Johnsongrass, Canadathistle, curly dock, field chickweed, dandelion, Russian knapweed aster,horsetail ironweed, sesbania, cattail, wintercress, horsenettle,nutsdge, milkweed, sicklepod, and the like.

The compounds of this invention are also useful as aquatic algicides,aquatic plant growth regulators and aquatic herbicides. Thus thisinvention provides a method for controlling aquatic plant growth byapplying an aquatic herbicidally effective amount of a compound of thisinvention to aquatic plants to be controlled or to the water in whichthe plants are growing. Typical of the various species of aquaticvegetation which the herein described compounds may be used to controlare aquatic algae, such as, for example, Chlorella vulgaris, Scenedesmusquadricanda, Anacystis nidulans and the like; aquatic plants, such as,for example, Hydrilla, Coontail, Duckweed, S.Naiad, Eurasion milfoil,Cambomba, Sago pond weed, water hyacinth and the like.

The aquatic plant growth control method of this invention is practicedby adding the active oxadiazol-imidazolidinone compound to the watercontaining the submerged, emergent, ditchbank or floating aquaticplants, or otherwise contacting the plants with the active compounds,for example, by applying the compounds to the sub-aqueous soil in whichthe aquatic plants are rooted. The compounds may be applied to the wateras dusts when admixed with a powdered solid carrier such as bentonite.Fuller's earth, diatomaceous earth, or various mineral silicates, e.g.,mica, talc, pyrophyllite, and clays. The compounds may also be mixedwith surface-active dispersing agents to form concentrates to facilitatedispersion in water and to improve the wetting properties when used assprays. If desired, the compounds may be mixed with a powdered solidcarrier, together with a surface-active dispersing agent, so that awettable powder may be obtained which may be applied directly, or whichmay be shaken with water to make an aqueous dispersion for applicationin that form. These wettable powder formulations suitably contain fromabout 25 to about 85 percent by weight of the active ingredient, i.e.,an aquatic growth regulating compound coming within the scope of thegeneral formula. The compounds may be dissolved in an oil, such as ahydrocarbon or chlorinated hydrocarbon oil, and the oil solution of thecompound dispersed in water with the aid of a surface-active dispersingagent to give a sprayable aqueous dispersion. Such surface activedispersing agents may be anionic, nonionic, or cationic surface-activeagents. Such surface-active agents are well-known, and reference is madeto Hoffman et al., U.S. Pat. No. 2,614,916, columns 2-4 for detailedexamples of the same. The compounds useful in this embodiment of theinvention may also be applied by the aerosol method. Solutions for theaerosol treatment may be prepared by dissolving the compound directly inthe aerosol carrier, which is a liquid under pressure, but which is agas at ordinary temperature (e.g. 20° C.) and atmospheric pressure; or,the aerosol solution may be prepared by first dissolving the compound ina less volatile solvent, and then admixing such solution with the highlyvolatile liquid aerosol carrier.

Further, the compounds useful as aquatic growth regulators can also beapplied in an invert emulsion formulation. An invert emulsionformulation is prepared by first making a solution of an aquatic growthregulating compound in heavy oils, such as diesel fuel, inverting oil,and the like, and combining the thus obtained solution with water underhigh shear stirring. The thick emulsion is placed in the water and sinksto the bottom of the lake, pond, or the like, and the aquatic growthregulator is gradually released to control the growth of the aquaticplants.

The compounds useful as aquatic growth regulators can also be applied aspellets which are prepared from a mixture of about 5% of the activeingredient, about 85% clay, and about 10% water, all percentages beingby weight. The mixture is then extruded through a pellet mill using asuitably sized die, e.g., about 1/8 in. diameter. The extruded pelletsare about 1/8 in. by 11/2 in., and are typically dried to about 8%moisture content.

The method of controlling aquatic plant growth provided by thisinvention is practiced by adding to the water containing the submergedor floating plants a growth-regulating or herbicidal amount of one ofthe herein-disclosed compounds, such that a concentration of from about0.01 to about 1 ppm. of the active compound is attained. A preferredmethod of aquatic plant growth regulation provided by this invention isdirected toward the control of plants such as water hyacinth. Suchplants can be controlled by foliar or root application of a compound ofthis invention at a rate of about 0.01 to about 1.0 pounds per acre(about 0.011 to about 1.1 kg/ha).

The optimum concentration of active compound for any specific aquaticweed control problem varies with the temperature, the species to becontrolled, and the shape of the body of water to be treated. At higherwater temperatures, less compound is generally required for a givendegree of control than is needed at lower temperatures. When used tocontrol algae of aquatic plant growth, the compounds will usually beemployed at concentrations of about 0.1 to about 10 ppm. In terms ofpounds of compound per acre of water one foot deep, 0.1 to 10 ppm. isequal to about 0.3 to about 30 pounds per acre of water one foot deep.

Although the invention has been described in considerable detail by theforegoing, it is to be understood that many variations may be madetherein by those skilled in the art without departing from the spiritand scope thereof as defined by the appended claims.

We claim:
 1. A method for controlling the growth of terrestrial plantsby contacting the plants or the soil in which the plants are growingwith a terrestrially herbicidally effective amount of compoundrepresented by the formula: ##STR15## wherein: A is ##STR16## R is alkylor haloalkyl of up to 6 carbon atoms, cycloalkyl of from 3 to 8 carbonatoms, alkenyl or alkynyl of up to 5 carbon atoms, -R⁴ -O-R⁵ or R⁴--S--R⁵ wherein R⁴ is alkylene of up to 6 carbon atoms and R⁵ is alkylof up to 6 carbon atoms, ##STR17## wherein Z is nitro, halogen,trifluoromethyl or R⁵ and n is 0, 1, 2, or 3;R¹ is hydroxy, halogen,##STR18## wherein R⁶ is alkyl or haloalkyl of up to 6 carbon atoms,cycloalkyl of from 3 to 8 carbon atoms, alkenyl or alkynyl of up to 5carbon atoms or ##STR19## wherein Z¹ is nitro, halogen, trifluoromethyl,alkyl or alkoxy of up to 8 carbon atoms and n is 0, 1, 2 or 3 or##STR20## wherein R⁷ and R⁸ are the same or different and representhydrogen, alkyl or haloalkyl of up to 6 carbon atoms; or R⁷ can be##STR21## R² is hydrogen, hydroxy, alkyl, or haloalkyl of up to 4 carbonatoms or allyl; and R³ is alkyl of up to 3 carbon atoms or allyl.
 2. Themethod according to claim 1 wherein said compound has R and R³ as alkyl,R¹ as hydroxy and R² as hydrogen or hydroxy.
 3. The compouond usedaccording to the method according to claim 2 which wherein said compoundis3-[5-(1,1-dimethylethyl)-1,2,4-oxadiazol-3-y1]-1-methyl-4-hydroxy-2imidazolidinone.4. A terrestrial herbicidal composition containing a compound or mixtureof compounds defined in claim 1 and a terrestrially acceptable carrier.